1. Field of the Invention
The present invention relates to an angular deceleration sensor which is used to detect an angular deceleration above a predetermined value of a wheel as a detected subject during the control of an antilock brake device for vehicles, for example, such as motorcycles and automobiles, and more particularly to an improvement in an angular deceration sensor wherein a flywheel is rotatably and slidably carried on a drive shaft operatively connected to the wheel rotating in a fixed direction, and between the drive shaft and the flywheel are interposed in series a clutch which normally transmits a driving torque of the drive shaft to the flywheel and allows, when the angular deceleration over a predetermined value occurs in the wheel, the flywheel an overrun rotation, and a cam mechanism for imparting an axial displacement to the flywheel in response to the overrun rotation thereof, the axial displacement of the flywheel being released as an angular deceleration signal.
2. Description of the Prior Art
A conventional angular deceleration sensor of this kind uses, as a clutch, a friction clutch which acts in both one and the other rotational directions (See Japanese Patent Application Laid-Open No. 126241/1983).
The clutch for the angular deceleration sensor of this kind has to provide two functions, one wherein the flywheel is accurately permitted to be slipped to provide the overrunning when an angular deceleration above a predetermined value occurs in the detected subject, and the other wherein the driving torque of the drive shaft may be positively transmitted to the flywheel. However, as in the prior art, where a friction clutch which acts in both one and the other directions is used as a clutch, when a friction force of the friction clutch is adequately set so as to accurately create the overrun rotation in the flywheel, an insufficient friction force results for driving the flywheel from the drive shaft, and when the subject is rapidly accelerated in rotation, there is a fear that the clutch becomes slipped for a short period of time, as a result of which the flywheel fails to follow the drive shaft.